Ewl_Widget      *ewl_io_manager_convert(Ewl_Widget *w,
                                        const char *from_mime, 
                                        const char *to_mime);
unsigned int     ewl_io_manager_can_convert(const char *from_mime, 
                                                const char *to_mime);

void             ewl_io_manager_plugin_mime_register(const char *mime,
                                                Ewl_IO_Manager_Plugin *plugin);

void             ewl_io_manager_plugin_convert_register(const char *from_type, const char *to_mime,
                                                Ewl_IO_Manager_Plugin *plugin);


The _mime_register is used to specify mime types that we load/save. So:

_mime_register("application/pdf", pdf_plugin)
_mime_register("image", image_plugin),
_mime_register("text", text_plain_plugin)
 _mime_register("text/html", html_plugin)


the _convert_register calls are used to register what we can convert. They take the widget type name and the mime we convert too. so:

_convert_register("widget/text", "application/pdf", pdf_plugin);
_convert_regiseter("application/pdf", "widget/pdf", pdf_plugin);
_convert_register("widget/pdf", "image/jpeg", pdf_plugin,);
_convert_register("widget/pdf", "image/png", pdf_plugin);

_convert_register("widget/text", "text/html", html_plugin);
_convert_type("widget/image", "image/png", image_plugin);